Impulse transmitter



Nov. 13, 1934. w R, DAVE, 1,980,190

IMPULSE TRANSMITTER Filed March 4, 1932 2 Sheets-Sheet 1 K4 K3 K2 INVENTOR WR. DA V/S ATTORNEY Nov. 13, 1934. w. R. DAVIS IMPULSE TRANSMITTER Filed March 4, 1952 2 Sheets-Sheet 2 INVENTOR By (RDA V/S. @(gc AT TORNEY Patented Nov. 13, 1934 Ill/[PULSE TRANSMITTER William R. Davis, Aldwych, London, England, assignor to Western Electric Company, Incorporated, New York, N. Y., a corporation of New York Application March 4, 1932, Serial No. 596,758 In Great Britain March 19, 1931 3 Claims.

This invention relates to electric signaling or selective systems and more particularly to registering and controlling mechanisms for use in such systems.

The present invention has been devised in connection with so-called train dispatching systems, but is applicable to any other electric signaling or selective system in which similar conditions are met.

Train dispatching systems are telephone party lines comprising usually one control station and a number of way-stations. Selection of a particular station is usually performed by transmitting a code comprising seventeen impulses divided into three trains in a manner characteristic to the station.

The code is usually transmitted by mechanical senders or keys each individual to a waystation, which are comparatively expensive.

The object of the invention is to provide register controlling means, preferably of the all relay type, to replace the mechanical code senders, one per code, previously used in such systems.

Such register controlling means is cheaper than the mechanical senders, and the operators keyset or the like takes up much less room than the previous arrangements.

In such systems the codes are transmitted by alternate impulses of opposite polarity caused by the alternate operation and release of a relay.

If one train of impulses of a code ends with the relay operated, the next train must begin by an impulse caused by deenergization of the relay.

One feature of the invention comprises a register controller or relay counting chain so constructed and arranged that it is adapted to control the transmission or reception of a train of impulses beginning with either of two difierent kinds of impulse.

Further it is advisable to retain the same code arrangement since if this is done the standard selectors can be used at the way-stations or the like.

Generally in such systems one only of three impulse trains in any code ever exceeds seven in number, the possible maximum being thirteen.

Another feature of the invention comprises a plurality of relay registers, adapted to register a digit of a code, and an additional relay register adapted to be individually associated with, or to replace, any one of said plurality of registers, to register a digital value above the capacity of each of said plurality of registers. One embodiment of the invention will be described below with ref erence to the drawings wherein:

Fig. 1 shows a set of thirteen keys and a relay register,

Fig. 2 shows the impulse sending and counting devices.

The system will first be described in brief.

The system provides a means whereby with the use of numbered keys, step-by-step relays and a pendulum relay, a three-digit code of impulses is originated and transmitted over lines, the number of impulses per digit depending upon the keys depressed and the total number of impulses remaining constant for each code.

This system is designed primarily for use in train dispatching systems such for instance as shown in Fig. '7 of J. C. Field Patent 1,343,256 and replaces the selector keys and selector key case normally used.

Since the impulse receiver at way-stations is the standard selector, the total number of impulses per code in this case is 1'! and means are provided for the transmission of any of the 4'7 codes available for such selectors.

Keys numbered consecutively from 2 to 13 are provided and these are used for setting up the code it is desired to transmit. Three keys corresponding to the digit values of the code are depressed in rotation causing the code to be set up on marking relays. On the release of the third key a pendulum relay is operated to transmit impulses to line. The outgoing impulses are counted on relays and when the number transmitted equals the number marked further impulses are prevented from going to line. Y The second and third digits are similarly transmitted, a pause in impulsing being provided at the end of each digit, and at the conclusion of the third digit the apparatus is restored to normal.

In addition to the numbered keys, a general call key is provided which will cause 17 impulses to be transmitted to operate all the selectors on the lines to their ringing terminals. Further, in case an error in setting up the code is made, a cancel key may be operated to restore the apparatus to normal before the impulses are transmitted.

Referring to the drawings, K2, K3, K4, etc., are the sending keys which are of the non-locking type, and A2, A3, A4, etc., B2, B3, B4, etc. and C2, C3, C4 etc. are the marking relays for the first seven impulses for the first, second and third digits respectively. Relays C8, C9, C10 etc., are used for marking higher digit values and an economy in relays is effected by using one set only for this purpose since any of these high values can only appear once in each code, by employing 110 relays H1, H2 and E3 to determine the digit in which the marking shall apply. Relays D1, D2 and D3 are operated in succession by the first, second and third depressions of the keys. Relays D1 and D2 insure that the marking relays appropriate to the proper digit are operated in .their correct sequence. Since relays D1 and D2 serve to transfer a source of current supply from one set of marking relays to another they will, for the purpose of identification, be hereafter referred to as marking transfer relays. "RelayD3, which is operated after the release of .the third key, connects the line battery to the line relay contacts and starts the pendulum relay PR .lmpulsing. Relay D3 will hereafter be referred to as line battery relay D3. The numbered relays 21, 22, 23, 24 etc., are counting relays whichare operated in rotation by the outgoing impulses and, since these relays have to count half cycles, because for selector impulses the make and the break each count as one impulse, it is necessary to employ relays L1, L2, L3 and L4 to change the marking in the case of digits following-digits with an odd number of impulses. Relays L1, L2, L3 and Li-will-be hereafter referred to as marking change relays. To prevent impulses being transmitted to line after the correct number in the digit has been counted relays O1, O2 andOB are provided in the case of first, second and third digits respectively with an odd number of impulses in the digit. Since the'odd numbered impulses are made on themaking of contacts, relays O1, O2 and 03 will be referred to hereafter as make impulse holding relays. Relays E1, E2 and E3 are provided in the case of first, second and third digits respectively with an even number of impulses in the digit. Since the even numbered impulses are made on the breaking of contacts, relays E1, E2 and E3-will be referred to hereafter as break impulse holding relays. Relay P is a line relay the contacts of which'are capable or placing battery reversals over the lines. Relays S1 and S2 operate at the end of the first and second digits to remove the first andsecond and to apply the second and third markings respectively for the digits to the counting relays. Relays'sl .andS2 will be hereafter referred to as counting transfer relays. Relay F is the final cut-off relay which restores theapparatus to norinal after the complete transmission of the code.

Considering the keys 2, 3, 1, 5, 6 and 7, it will be seen that the depression of one of these for the first digit will operate momentarily a corresponding A relay over a back contact of marking transfer relay D1, and the relay so operated will lockup over a second winding, itsown make contacts and a contact of relay F. "The depression of any of these keys also provides a circuit for energizing the lower winding of marking transfer relay D1. For instance if key K2 is depressed relayDl will be energized over the following circuit: ground, conductor 101, conductor 102, lower contact of key K2, conductor 103, lower armature and back contact of relay D1, lower winding of relay. D1 ..to battery. Relay .Dloperates fully through its lower and upper windings, innermost .upper armatureand front contact, conductor I04, conductor 1.05, conductor 106, conductor 107, lower armature and back contact of relay F to ground on the release of the key and transfers the negative'feed 108 from the common side of the A relays to the common side of; the l3 relays so that no further A relays can be operated. "The depression of another key in the group K2to rK'? will operate a relay in the B group which will lock up over a locking winding and its own contacts as did the A relay for the first digit. The lowermost armature of D1 has also changed over to a front contact so that the depression of the second key energizes thelower winding of marking transfer relay D2 which relay will operate fully on its lower end and upper windings on the release of the second key to transfer the negative battery lead 108 to the C group to enable marking to be made for the third digit. Contacts on marking transfer relay D2 provide that the depression of the .thi-rdekey operates line battery relayD3-andsthe release of the third key enables line :battery relay D3 to operate fully through its lower and upp'er'windings to complete a circuit. for the, pendulum'relay PR and to connect the line .battery 109 to the contacts of line relay P which transmits the impulses to line. The circuit lows: battery connection 110 of the pendulum relay BR, resistance 111, winding :of the pendulum relay PR, conductor 112, lower armature-and front contact :of'relay D3, conductor 1'13, conductor 106, conductor 107, lower armature andback contactof relay F to ground. The pendulum relay closes 'its contacts and shorts out its own Winding and releases. This alternate energization and deenergization of the pendulum relay continues as long as the system is in operation which is terminated by energization of relay'F.

Considering the keys 8, -9, 10 etc., it will be seen that the depression cr me of these operates a corresponding vmarking relay C8, C9, C10 etc., and that associated with these are'digit determining relays Hl, =H2and H3 which can operate only on the first, second or third digit respectively. TheC relay applies the marking to .the first, second .or third digit according to-whether digit determining relay H1,'H2 or H3 is-ope rated. Ithas been shown that after the third key has been released the pendulum relay PR which "is so constructed that it successively closes and opens its contacts while its circuit-is maintained through contacts of relay D3 andrelay 'F begins 'forthemendulum relay PR may be traced as foltoimpulse line relay P through back contacts 1 on break impulse ho-lding relays E1, E2 and E3. At the same time these impulses .are counted by the counting :relays 21, '22, 23, etc., inthe following-manner. The first make period is conductedthroug'hback contacts on counting relays 22, 24, 26, 28, 30, 32-and 34 to the common point of the windings of counting relays 21, and '22. Relay '21'operates'and provides an earth through itsupper contacts and lowermost armature and back contact of relay .24 forthe winding of relay 22. "Relay 22 is temporarily short-circuitc-d by having a ground from'the lower'armature and back'contact of relay'F but, on thesecond impulse which is a break period, the removal of the earth by the pendulum'relay PR from the common point of the windings of counting relays 21 and '22 will enable these two relays to operate in series. The next make period passes through break "contacts on counting relay 24 and make contacts on counting relay 22 tothe common point of the windings of counting relays'23 and 24. "Relay23 operates and prepares a circuit for relay 24'whichoperates in series with relay 23 on the succeeding break impulse. Relay 24 in operatingbreaks the circuitlfor relays 21 and 22 which deenergize. This operation of thecountin'g relays in succession is :carried on until, in the end, counting relays 33 and 734 are operated in series, when the next impulse will be diverted to relays 21 and 22 :again .to begin :a new operation lays.

of the counting relays. It is thus apparent that the counting relays operate in succession and are deenergized in pairs so long as impulses emanate from the pendulum relay PR and, since there are 14 counting relays, one complete operation of the counting group is sufficient to take care of the maximum number of impulses it is possible to obtain per digit. Counting relays 21, 23, 25, 27, 29, 31 and 33 count the make periods or odd impulses, the others count the breaks or even impulses.

Each pair of uppermost marking contacts on the marking relays is connected to a corresponding contact on the counting relays and through them an earth is applied for the O or E relays for each digit according to the marking.

Since the impulses begin with a make period, the odd impulses are makes in each case so that at the termination of a digit of an odd number of impulses, it is necessary, to prevent further impulses being transmitted to line, to keep the line relay P energized during the interdigital pause and the first impulse of the next digit will begin with a break period. For this reason, it will be seen that the make impulse holding O relays, when operated through marking contacts, provide an earth for the line relay P to maintain it in operation. The even impulses are break periods and in this case the line relay P is deenergized for each even impulse. Accordingly, the break impulse holding E relays when operated at the end of a digit break the impulsing circuit from the pendulum relay PR to the line relay P so that the latter remains deenergized during the inter-digital pause. Relays 01 and E1 are associated with the first digit and they can be operated through marking contacts on the marking relays and corresponding contacts on the counting relays and through 10wer back contacts on the counting transfer relays S1 and S2 to terminate impulses comprising the first digit. 12 is the maximum even number of impulses it is possible to have in one digit and counting relay 32, w ich is operated on the 12th impulse, is provided with make contacts to supply earth through make contacts on the break impulse holding E relays to the lower winding of counting transfer relay S1. Since one of the break impulse holding E relays will be operated at that time, this circuit is complete. In the case of the odd number of impulses, the earth is supplied through break contacts on counting relay 21, make contacts on the make impulse holding O relays and a make pair on relay 34. Counting transfer relay S1 will operate fully only when the earth is removed from the midpoint of its winding. For an even number of impulses this earth is removed on the operation of counting relay 34 since this relay breaks the circuit for counting relay 32. As has been explained, for an even num ber of impulses, the line relay P is held unoperated so that the first make impulse in the new digit is counted on relay 21 and received on the line relay P for transmission to line since counting transfer relay S1 breaks the circuit for the break impulse holding E relay to reconnect line relay P to the pendulum relay contacts. In the case of an odd number of impulses in the digit it is necessary to operate counting transfer relay S1 completely at a time when the line relay P would normally be operated by the pendulum relay PR, since the line relay P is being held operated during the interdigital pause by the operation of one of the make impulse holding 0 re- This is done by maintaining the earth on the mid-point of the windings of relay S1 through the back contacts on relay 21, and when relay 21 operates on what should be the first impulse of the second digit, the line relay P will remain operated when it is transferred to the pendulum relay circuit. In this way the first impulse is lost and in order that the markings and countings shall not be affected by this lost impulse, marking change relays L1, L2, L3 and L4 are operated to advance the markings one impulse. The marking change L relays are operated by the corresponding make impulse holding O relays, that is L1 and L2 are operated by 01 in the case of an odd number of impulses in the first digit, L3 and L4 are operated by relay O2 in the case of an odd number of impulses in the second digit.

As relay S1 was operated at the termination of the first digit, so relay S2 is operated at the termination of the second digit and at the conclusion of the third digit when the code has been transmitted relay F is operated to break the looking circuits for all relays.

As an example, and in order that the circuit may be more clearly understood, consider the transmission of the code 69-2. Key 6 will first be depressed which will complete a circuit for relay A6 from earth, conductor 101, upper key contacts of key K6 lower, winding of relay A6, back contact and uppermost armature of relay D1 to negative battery 108. Relay A6 will operate and a circuit for its locking winding will be complete from negative battery, upper winding of relay A6, contacts of relay A6, conductor 114, conductor 105, conductor 106, conductor 107, lower armature and back contact of relay F to earth. The depression of the key K6 also applied earth through the back contact and lowermost lever spring of the change-over contacts of marking transfer relay D1 to the lower winding of that relay and the release of the key K6 enables relay D1 to operate fully through its lower and upper windings, removing the negative battery from the A group of relays and transferring it through the uppermost lever spring and front contact of relay D1 and. uppermost lever spring and back contact of relay D2 to the B group. Key K9 will now be depressed which will energize relay C9 over the circuit-earth, conductor 101, uppermost key contacts of key K9, winding C9 to negative battery. Relay C9 will lock up over its own make contacts and the lower armature and back contact of relay F. The depression of the key K9 also energized digit determining relay H2 over the circuitearth, conductor l'0l,"key contacts, conductor 115, conductor 116, winding H2, conductor 117, back contact and uppermost lever spring of marking transfer relay D2, front contact and uppermost lever spring of marking transfer relay D1 to negative battery. Relay H2 has two windings similar to those shown in the relays A2 to A7 and will lockup over its own contacts and the back contact and lower armature of relay F. With marking transfer relay D1 operated by the first key, the depression of the second key completes a circuit through earth, conductor 101, lower key contacts, conductor 103, lower lever spring and front contact of D1, lower lever spring and back contact of relay D2 for the lower winding of marking transfer relay D2 and the release of key 9 enables marking transfer relay D2 to operate fully, transferring the negative battery for the B group of relays to the C group. Depression of key 2 operates relay C2 over the circuit-earth, conductor 101, upper key contacts, conductor 118, lower winding C2 conductor 119 back contact and lever spring of line 'battery relay D3,'front contact-and lever spring of marking transfer relay D2, front contact and lever spring of -marking transfer relay D1 to negativebattery 108. "Relay C2 locks'up over its own contacts and the back contacts of relay F by way'of conductor 120, conductor 105, conductor 106 and conductor 107. The release of K2 also operates line battery relay D3 'fully andcontactson this relay complete a circuit 'for the pendulum-relay PR' and apply line battery 109 tothe contacts of the line impulsing relay P. The-condition now is that relays H2, A6, C9 andC2 are operatedand locked up over back contacts of relay F, relays D1, D2 and D3 are similarly locked and the pendulum relay PR is ready to impulse. The impulses have the following effect:

Impulse 1. (make) Completes a circuit from earth, through back contacts on relay F, lower contacts on D3, lowermost pendulum relay contacts, back contacts on relays'22, 24, 26, 28, 30, 32, 34 to common side of the windings of counting relays 21 and 22. Relay 21 operates; Relay P operated (1 impulse to line). Relay P is operated over the following circuit: ground, back contact and lower armature' of relay F, conductor 107, conductor 106, conductor 113, lower armature and front contact of relay D3, conductor 112, upper armature and front contact of pendulum relay PR, conductor 124, break contacts of re1ays'E3, E2 and E1 which are in series, conductor 125, conductor 126, Wind ingof relay P to battery.

Impulse 2. (break) "Relays 21 and 22 operate in series over thecircult from earth, front contact and lever spring of relay 21, break contacts on relay -24, winding of relay 22, winding of relay 21 to negative battery. Relay P unoperated (2 impulses to line) Impulse 3. (make) Relay 23 operates over the circuit from pendulum relay contacts, impulsewire, back'contacts on relay 24, make contacts on relay 22, winding of relay 23, to negative battery. Relay'P operated (3'impu1s'es to line). i V

Impulse 4. (break) Relays 23 and 24 operate in series over the circuit from earth, make contacts on relay 23, break contacts on relay 26. winding-of relay 24, winding of relay 23, to negative battery. Relays 21 and 22 deenergize since their circuit is broken by the breakcontacts on relay 24. 'Relay P unoperated (4 impulses to line) Impulse 5. (make) Relay 25 operates in the same manner as relay 23 operated on the third impulse. Relay P operated (5 impulses to line).

Impulse 6. (break) own-make-contacts. Its breakgcontacts prevent further'impulses :from reaching the line relay P.

. Impulse 7. (make) Relay 2'7 operates. Relay P remains unoperated (inter-digital pause) Impulse 8. (break) Relays 27 and 28 operate in series. Relays 25 and 26 deenergize. Relay P remains unoperated (inter-digital pause) Impulse 9. (make) Relay 29 operates. Relay P remainsunoperated (inter-digital pause).

Impulse 10. (break Relays 29 and 30 operate in series. Relays 2'7 and 28 deenergize. Relay P remains unoperated (inter-digital pause).

Impulse 11. (make) Relay 31 operates. Relay P remains unoperated inter-digital pause) Impulse 12. (break) Impulse 13. (make) Relay 33 operates. Relay P remains unoperated (inter-digital pause) Impulse 14. (break) 'Relays 33 and 34 operate in series. Relays 31 and32 are deenergized. Relay P remains unoperated (inter-digital pause). Removing the earth from the midpoint of the windings of counting transfer relay S1 by the deenergizing of relay 32 enables counting itransferrelaysl to operate fully With'its'two windings in series'over break contacts on relay F. Relay E1 deenergizes enabling further impulsesto reach the line relay from the pendulum-relay and this occurs during a break impulse so that relay P is ready to receive the next impulse which will be a make.

14 impulses have now been counted and the next impulse will be the first of the second digit.

2ND Drorr Impulse 1. (make) Relays 33 and 34 are operated in series and this first impulse operates relay 21 over the circuitearth, impulse wire, break contacts on relay 22, make contacts on relay 34, winding of relay 21 to negative battery. Relay P operates (l impulse to line).

Impulse 2. (break) Relays 21 and 22 operate in series. Relays 33 and 34 deenergize. RelayP is unoperated (2 impulses to line).

Impulse 3. (make) Relay 23 operates. Relay P operates (3 impulses to line).

Impulse 4. (break) Relays 23"and 24operate in series. Relays r21 Ki l-ll and 22 are deenergized. Relay P is (4 impulses to line).

Impulse 5. (make) Relay P operates (5 imunoperated Relay 25 operates. pulses to line).

Impulse 6. (break) Relays 25 and 26 operate in series. Relays 23 and 24 are deenergized. Relay P is unoperated (6 impulses to line).

Impulse 7. (make) Relay 27 operates. Relay P operates (7 impulses to line).

Impulse 8. (break) Relays 2'7 and 28 operate in series. Relays 25 and 26 are deenergized. Relay P is unoperated (8 impulses to line).

Impulse 9. (make) Relay 29 is operated. Relay P is operated (9 impulses to line). The marking for the second digit is provided by relay C9 and make contacts on this relay provide an earth through contacts 9b on relay H2, through contacts on relay L2 to contact 29b of relay 29 for relay 02 which operates over the front contact and lever spring of the change-over contacts of relay S1, back contact and lever spring of the change-over contacts of relay S2 to negative battery. Contacts on relay 02 provide an earth for the winding of the line relay P which is already energized so that so long as 02 is operated breaks from the pendulum relay will not affect it and further impulses are prevented from going to line. When once operated make impulse holding relay 0 looks up over its own make contacts.

Impulse 10. (break) Relays 29 and 30 operate in series. Relays 2'7 and 28 are deenergized. Relay P remains operated (inter-digital pause) Impulse 11. (make) Relay 31 operates. Relay P remains operated (inter-digital pause).

Impulse 12. (break) Relays 31 and 32 operate in series. Relays 29 and 30 are deenergized. Relay P remains operated (inter-digital pause). It should be noted that since no E relay is operated the earth supplied by contacts on relay 32 tothe S relays is not effective.

Impulse 13. (make) Relay 33 operates. Relay P remains operated (inter-digital pause). I

Impulse 14. (break) Relays 33 and 34 operate in series. Relays 31 and 32 are deenergized. Relay P remains operated (inter-digital pause). Make contacts on relay 34 complete a circuit from earth, break contacts on relay 21, make contacts on relay 02, make contacts on relay 34, uppermost lever spring and front contact of the change-over contacts of relay S1 (operated) lower winding of relay S2 to negative battery.

Impulse 15. (make) Relay 21 is operated and the earth provided by its break contacts to the lower winding of relay S2 is removed so that relay S2 operates fully with its two windings in series and removes the negative battery feed from relay 02 which deenergizes and permits further impulses from the pendulum relay to reach the line relay P. Since this impulse is a make period and relay P has been held operated it is inefiective as regards line impulses and the first impulse of the third digit will be a break period.

When relay O2 operated on the 9th impulse of the second digit it completed a circuit for marking change relays L3 and L4 which locked up over their own contacts and the back contacts of relay F to earth. This advances the markings for the third digit one impulse and the marking imposed by relay C2 and its contacts 20 is advanced from contact 220 to 230 by change-over contacts on relay L3. I

3RD DIGIT Impulse 1. (break) Relay 21 is already operated and this first impulse of this, the 3rd digit, operates relays .21 and 22 in series. Relays 33 and 34 deenergize. Relay P is unoperated (1 impulse to line).

Impulse 2. (make) Relay 23 operates: Relay P operates (2 impulses to line). With relay 23 operated the marking from relay C2 transferred to contact 230 by marking change relay L3 operates'relay 03 through front contact and lever spring of relay S2 to negative battery. Make contacts on this relay provide an earth for the winding of relay P which being operated remains operated so long as relay O3 is operated. Relay 03 looks up over its own contacts. The total number of 17 impulses has now been sent and the selector at the way-station coded 6-9-2 is now operated to its ringing terminal.

Impulse 3. (break) Relays 23 and 24 operate in series. Relays 21 and 22 deenergize. Relay P remains operated (ringing period).

Impulse 4. (make) Relay 25 operates. Relay P remains operated (ringing period).

Impulse 5. (break) Relays 25 and 26 operate in series. Relays 23 and 24 deenergize. Relay P remains operated (ringing period).

Impulse 6. (make) Relay 27 operates. Relay P remains operated (ringing period).

Impulse 7. (break) Relays 2'7 and 28 operate in series.

and 26 deenergize. (ringing period).

Relays 25 Relay P remains operated Impulse 8. (make) Relay 29 is operated. Relay P remains operated (ringing period) Impulse 9. (break) system is restored to normal.

Impulse 10 (make) Relay 31 operates. Relay P remains operated (ringing period).

Impulse 11. (break) Relays 31 and 32 operate in series. Relays 29 and 30 deenergize. Relay P remains operated (ringing period).

Impulse 12. (make) Relay 33 operates. Relay P remains operated (ringing period).

Impulse 13. (break) Relays 33 and 34 operate in series. Relays31 and 32 deenergize. Make contacts on relay 34 complete a circuit from earth, back contacts of relay 21, make contacts of relay 03, make contacts of relay 34, lever spring and front contact of the change-over contacts of relay S1, lever spring and front contact of relay S2, to the winding of relay F which operates and breaks the earthlocking circuits for all relays so that .ihe

Relay P in restoring to normal sends: a final impulse to. line to restore the selector at the distant station.

The cancelkey can be operated if incorrect keys are depressed for either the first or. second digits and it has the effect of operating relay F to break the locking circuit for the marking relays 'operated by those keys. 1

The general call key when depressed open ates relay'GC which locksup over back contacts on relay F and marks contacts. 23b.and"22c. Also, when released, it, operates relayQDB fully which connects line battery to'contact's of relay P and alsocompletes the circuit for'th'e pendulum relay'toimpulse' The impulses are counted on the relaysas followsi-' Impulse '1' (make) on relay 21,. Impulse 2 (break) on relay 22, Impulse 3 (make) on relay 2'3 and so on, the 14th impulse being counted on relay 34, the 15th. on relay 21 again, the, 16th on relay 22. and the 17th on'irelay'23."

When relay 32'operate'd it completed the .circuit for the lower winding of relay Sl'from'earth, contacts on relay'32, break contacts on relay GC, lever spring and back contact on relay S1, winding'of S1 to negative battery; Relay S1 operates fully on the operation of relay 3'4, since at this point relay 32 isdeenergized toremove the earth from the mid-pointof the two windings of relay S1. Change-over contacts on relay'Sl prepare a circuit topick up the marking on the lfse't of contacts and the marking, imposed by relay G0 on contact 23b through contacts on relay L1, causes relay O2 to operate; Contacts on this latter, relay. maintain an earth to relay Pzwhich remains operated until the end ,of. thisdigit, As shown when describing the circuit for the Q-impulse digit in the above 'code' example, relay P is not freeto follow impulses again until relay 21 operates. The impulse operating relay 21 is a make so that relay P is still operated. The next impulse, a break, operates relays 21 and 22 in series and relay Pis deenergized sending a final impulse, to line to restore the selectors at the distant way'stations to normal". A marking is imposed on contact 22c by contacts on reiaycc so that when relay ,2. .isoperated a circuit is completed for relay E3 which operates and locks upover contacts on relay S2 whicho'perates fully by contacts on relaysO2, and 34- when relay"2 1 operates. Relay E3 maintainsrel'ay Pi deeriergized by breaking the impulse wire from the peri dulum relay. 1 On the third count by the relays when rela 32 operates, a circuit is completed for relay F throughcontacts on, relays GC, S1' and S2. In

operating relay F breaksthe locking circuit for all relays and the system is restored to normal.

What is claimed is:

1. A transmitter for a selective signal-system comprising two groups of manually operated keys, three groups of marking relays controlled by the first group of. keys, a single group of marking relays controlled by the second group ofkeys, means whereby the first group oflkeys and the three groups of marking relays controlled there--. by operate to set up code. signals having three digits of a predetermined low number of impulses-and the second group of keys and the single group of "marking relays controlled thereby operate to set up code signals of one digit. of a higher number of impulses than is possible in the first group of keys and the three groups of marking'rel'aysfmarkin'g transfer relays operating in sequence and common to-the groups of keys, a source of current supply for the marking relays, means including contacts operated by said markingtransfer relays upon operation: of a key in I either group to transfer'the source ofcurrent supply from one group of marking relays to another, digit determiningrelays connected tothe second group of keys and to contacts of: said marking transfer relays, means wherebyrsaid digit determining relays and said marking transfer relays operate to replace one of the groupst'of marking relays controlled by the first groupv of keys by the single group of marking relays con: trolled by the second group of keyswhen a key in the second group is. operated, marking con.- tacts controlled by the digitdetermining. relays and connected to contacts controlled by the single group of marking relays for the second group of keys, a line battery, line contactsa line battery relay operating in sequence'withrthe last of said marking transfer relays tov connectthe. line bat;- tery to the linecontacts, a pulsing, pendulum type relay, said line battery relay haying contacts to close acircuit to s'aidv pulsing'pendulum type. relay, a line relay, reversible line contacts controlled by said line relay. and meansincluding a system of counting relays operating in'sequence and have ing contacts marked by. said marking relays. to control the operation of. said line relay.

2. A transmitter for sending. code signal/rim.- pulses of three digits to operate. selectors. com:- prising two groups "of. manually operated keys, the first group to set up digit signalsdup toiseven impulses, the second v group. to. set. ,up digit signals above seven im'pulsesfthr'ee groups of marking relays controlled by'ithe-keys of the first group, a single group of marking relays. controlled by the keys in the second group, a source of current supply for the'th ree groups of marking relays for the first group of keys, means including markin'g transferrela'ys' controlled by-said keys and operating in sequence to transfer the source of cur- 'saidmarki'ng relays and' said digit determining relays, means-whereby said markingtra'ns'fer relays and said digit determining relays operate to substitute the single group of marking relays controlled by the second group of keys for one of the groups of marking relays controlled by the first group of keys when a key in the second group is operated, a line battery, a line battery relay controlled by the manually operated keys and operating in sequence with the last of the marking transfer relays to connect the line battery to line contacts, a line relay, means including a pulsing relay operating to repeatedly send pulsations of current to said line relay, said line battery relay operating to close a circuit to said pulsing relay, reversible line contacts controlled by said line relay, and means including a system of counting relays operating in sequence and a system of make impulse holding relays and break impulse holding relays to control the operation of said line relay in accordance with contacts marked by said marking relays.

3. In a transmitter for sending code signals, two groups of manually operated keys, the first group representing digits up to a predetermined number of impulses, the second group representing digits above the number of impulses obtainable by any one key in the first group, three groups of marking relays controlled by the first group of keys, a single group of marking relays controlled by the second group of keys, marking transfer relays common to the two groups of keys and operating in sequence, digit determining relays controlled by said second group of keys,

a source of current supply for said three groups of marking relays and for said digit determining relays, marking contacts controlled by said three groups of marking relays, marking contacts controlled by said digit determining relays and said single group of marking relays, means whereby said marking transfer relays operate in response to the operation of the keys in either group to transfer the source of current supply from one group of the three groups of marking relays to another, means whereby said marking transfer relays and said digit determining relays operate to substitute the single group of marking relays for one of the three groups of marking relays when a key in the second group is operated, a line battery, a line battery relay operating in sequence to the last of said marking transfer relays, in response to the operation of said keys, to connect the line battery to line contacts, a pulsing relay, contacts controlled by said line battery relay to close a circuit to said pulsing relay, a line relay receiving current pulsations through said pulsing relay, reversible line contacts operated by said line relay and means including a counting relay system and a system of make impulse holding relays and break impulse holding relays to prevent further movement of said line relay for interdigital pauses in the code signal, said counting relay system having contacts marked by said marking relays.

WILLIAM R. DAVIS. 

